351 Top End/reliability rebuild
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=38033
Printed Date: October-07-2024 at 12:26pm
Topic: 351 Top End/reliability rebuild
Posted By: mbshaw88
Subject: 351 Top End/reliability rebuild
Date Posted: January-28-2016 at 2:30pm
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At the end of the season I did a cold compression test on my Ford 351 (82 SN) and cylinders #3 & #4 were both reading around 80 psi, the rest were between 140-150. A couple drops of oil in the cylinders did nothing, so I'm assuming it's either valves or the head gasket based on the service manual. I was going to pull the motor/trans assembly and work on it. Other than fixing the compression I'd like to replace/check anything else I can while it's out. There was usually a good bit of oil near the bilge after driving all day, so replace the main seal? What do you guys recommend? Just start tearing it down and inspecting parts as I go? This is basically what I'm looking to do:
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davidg wrote:Replies:
Posted By: Hollywood
Date Posted: January-28-2016 at 2:36pm
| Don't throw a rear main at it until you find the leak (more likely dripping off the valve covers) |
Posted By: SNobsessed
Date Posted: January-28-2016 at 2:39pm
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I'll counter with: I have been burned by leaving an old seal in place while repairing something. It then started leaking after a while - did 2 repairs total! ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: tryathlete
Date Posted: February-01-2016 at 11:56pm
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If you are going to pull the motor and transmission, I'd have to ask myself how much I'd not want to do that again. If the answer was--somewhere north of Never Again, and even like Chinese girls say "long time", I'd consider: Rebuild transmission-- kits are cheap, replace oil pump and damper plate at the same time Replace valve guides, rocker arms, stem seals and of course the usual minimum 3 angle valve job.... I'd r do all gaskets and seals....i mean everything. Gasket set and a few hours time.... Paint the whole engine, Maybe do a thorough inspection on manifolds just because you can. Id inspect each cylinder wall visible above BDC for any scuffing or obvious damage too. All this stuff is pennies and an investment in uptime during the Summer. Of course....the engine is out so repack the rudder and prop shaft. Check all the cables--easy to replace while you're in the belly of the beast with nothing in the way. Sorry if you think I'm making more work for you. ------------- 2008 MasterCraft 197TT 1996 Nautique Super Sport 1988 Waterlogged Supra Mariah |
Posted By: mbshaw88
Date Posted: February-02-2016 at 1:07pm
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Appreciate the input guys The transmission is 2 years old. I Just want to pull everything out together as an assembly to make it easier. The boat ran great all summer, I just did the compression test as an end of the season check. I know I don't want to pull the engine again so might as well do it 100% and right the first time. But I'm terrified that I'm gonna get in to this thing and have a torn apart engine in mid July. For now I think I'm just gonna have to take off the head and see what the issue is before I commit to a full tear-down. |
Posted By: phatsat67
Date Posted: February-02-2016 at 1:23pm
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Look for traces of oil down the back of the heads to the bell housing like HW said. If you see that it probably isn't the rear main. If it isn't the rear main it would be way easier to leave the motor in it and plop on fresh heads. ------------- |
Posted By: MrMcD
Date Posted: February-14-2016 at 6:11pm
| I had low compression on my 1978 Ski Nautique 351W at 900 hours. I pulled the heads and replaced them. I could have had them rebuilt but I found a great deal on a set so I used them. It made the 900 hour engine purr like brand new again. I ran it 600 more hours and then sold the boat to upgrade. Did not need to remove the engine to swap heads. It was pretty painless doing it in the boat. I would pull the heads, see where your problem is and decide what to do about it at that point. A good machine shop can fix your heads. |